Santo Domingo, Dominican Republic
Havana, Cuba
Mexico City, Mexico
San Juan, Puerto Rico
Caracas, Venezuela

I would consider the logistics of a Japanese or Korean team travel-time-prohibitive, which is why they weren't included on the list, but (a) Central American/Caribbean team(s) would face no greater travel times than, say, a Seattle does. Would any/all of those cities be able to support a MLB team logistically and financially (consistent fan attendance, etc)?

Please feel free to comment on why or why not.